Air Quality Improves To 'Poor' Category After Light Showers In Delhi-NCR

Light drizzle across the Delhi-NCR significantly brought down the pollution level in the region with the Air Quality Index reaching ‘poor’ mark on Thursday. According to the Central Pollution Control Board, the AQI of Delhi was recorded at 267 after the rainfall. While Rohini had the cleanest air at AQI of 168, area around Dr Karni Singh Shooting Range recorded the worst AQI at 306. According to the experts, the rainfall is due to the peripheral impact of cyclone ‘Maha’. On Wednesday, after a week-long toxic smog, Delhi-NCR breathed a sigh of relief with the noticeable dip in the pollution levels. According to the Central Pollution Control Board, the Air Quality Index of Delhi was recorded at 241 in morning on Wednesday. Localities in Dilshad Garden and Sri Aurobindo Marg areas had the cleanest air. The AQI in both these areas was registered at 184. Even Anand Vihar breathed relatively clean air with AQI of 281. The worst locality in Delhi in terms of AQI was Bawana, which had pollution level at 305. The improvement of AQI from critical to very poor levels is due to surface winds. Neighbouring Ghaziabad also had better AQI. Vasundhara recorded lowest AQI at 275.

An AQI between 0-50 is considered 'good', 51-100 'satisfactory', 101-200 'moderate', 201-300 'poor', 301-400 'very poor' and 401-500 'severe'. An AQI above 500 falls in the 'severe plus' category. Despite the Supreme Court order, the stubble burning continues in the neighbouring states of Punjab and Haryana. However, many feel that the odd-even scheme has curtailed vehicular pollution in Delhi-NCR.

The India Meteorological Department said winds gusting up to 25 kmph were flushing out pollutants faster. "There are good chances of rains in northwest India on Wednesday night and Thursday due to a western disturbance. The precipitation will cover Delhi-NCR, Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Punjab, Haryana, Rajasthan and western Uttar Pradesh," head of IMD's regional weather forecasting centre of Kuldeep Srivastava, said. He said the situation will not be similar to that of Sunday when high humidity due to light rains led to the formation of more potent secondary particles.

Secondary particles are product of complicated atmospheric reactions between primary particles -such as particulate matter, sulphur dioxide and nitrogen dioxide directly emitted by stubble burning and vehicles - in the presence of other factors such as sunlight and moisture. Examples of secondary particles include sulphates, nitrates, ozone and organic aerosols.  

Srivastava said visibility levels improved to 3,000-3,500 metres in the afternoon, which is considered normal.

The worst smog was witnessed by Delhi-NCR after Diwali. A day after the festival, Delhi woke up to a hazy, smog-filled morning on October 28 with the Air Quality Index shooting to frightening 900 in some areas. Despite the Supreme Court ban, Diwali witnessed widespread use of firecrackers by people of Delhi-NCR. As predicted by the System of Air Quality and Weather Forecasting And Research (SAFAR), the morning air after Diwali was totally unbreathable.